Chemical Reactions and Equations: Class 10 Chemistry Q&A · Page 3
120 free answers on Chemical Reactions and Equations (Chemistry) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ChemistryClass 10ICSE
What is a redox reaction? Explain with an example. (b) When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced? Why? (c) In the reaction represented by the equation: MnO2 + 4HCl → MnCl2 +2H2O +Cl2 (i) Name the substance oxidized (ii) Name the oxidizing agent Name the substance reduced (iv) Name the reducing agent
A redox reaction is a reaction where oxidation and reduction occurs It is also called redox reaction. SO3(aq) + MnO4(aq) → SO4(aq) + Mn Oxidation happened for SO3and reduction happened for MnO4 Magnesium is oxidised as addition of oxygen to magnesium takes place leading to formation of magnesium oxide. (i) HCl (ii) MnO2(iii) MnO2 (iv) HCl
- ChemistryClass 10ICSE
What is an oxidation reaction? Identify in the following reaction (i) the substance oxidized, and (ii) substance reduced: ZnO + C → Zn +CO
Oxidation is the process when an atom loses its electron in a reaction. Or the addition of oxygen to a substance to increase the proportion of oxygen in its molecule and oxidation can be achieved without oxygen by the removal of hydrogen i.e. dehydrogenation. (i)Substance oxidized is C (ii) Substance reduced is ZnO
- ChemistryClass 10ICSE
Fill in the following blanks with suitable words: (a) The addition of oxygen to a substance is called whereas removal of oxygen is called . (b) The addition of hydrogen to a substance is called whereas removal of hydrogen is called . Anti-oxidants are often added to fat containing foods to prevent due to oxidation
Solution: Oxidation; Reduction;
- ChemistryClass 10ICSE
When SO2 gas is passed through saturated solution of H2S, the following reaction occurs: SO2 + 2H2S → 2H2O +3S In this reaction, which substance is oxidized and which one is reduced?
In this reaction the substance oxidised is H2S and the substance which got reduced is SO2
- ChemistryClass 10ICSE
Identify the component oxidized in the following reaction: H2S +Cl2→ S +2HCl
H2S is oxidized in the above reaction.
- ChemistryClass 10ICSE
In the following reaction between lead sulphide and hydrogen peroxide: PbS(s) + 4H2O2(aq) → PbSO4(s) +4H2O(l) (a) Which substance is reduced? Which substance is oxidized?
H2O2 PbS
- ChemistryClass 10ICSE
What type of reactions are represented by the following equations? (a) CaO + CO2→ CaCO3 (b) 2Na +2H2O → 2NaOH +H2 (c) Mg + CuSO4→ MgSO4 + Cu (d) NH4NO2→ N2 +2H2O (e) CuSO4 + 2NaOH →Cu(OH)2 +Na2SO4
Combination Displacement Displacement Decomposition Double displacement reaction
- ChemistryClass 10ICSE
Which of the following is a combination and which a displacement reaction. (a) Cl2 +2KI → 2KCl +I2 (b) 2K + Cl2 → 2KCl
Displacement Combination
- ChemistryClass 10ICSE
Balance the following chemical equations: (a) FeSO4→ Fe2O3 + SO2 + SO3 (b) Pb(NO3)2(s) →PbO(s) + NO2(g) + O2
2FeSO4→ Fe2O3 + SO2 + SO3 2Pb(NO3)2(s) → 2PbO(s) + 4 NO2(g) + O2 Both in the presence of heat and decomposition reaction takes place
- ChemistryClass 10ICSE
What type of chemical reactions is represented by the following equations? (i) A + BC → AC+ B (ii) A +B → C (iii) X → Y+ Z (iv) PQ + RS → PS + RQ (v) A2O3 + 2B → B2O3 + 2A
Displacement Combination Decomposition Double displacement Displacement
- ChemistryClass 10ICSE
What type of chemical reaction stake place when: (a) A magnesium wire is burnt in air? (b) Lime-stone is heated? (c) Silver bromide is exposed to sunlight? (d) Electricity is passed through water? Ammonia and hydrogen chloride are mixed?
(a) Combination. (b) Decomposition. (c) Decomposition. (d) Decomposition. Combination.
- ChemistryClass 10ICSE
What type of reactions are represented by the following equations? (i) CaCO3→ CaO + CO2 (ii) CaO + H2O → Ca(OH)2 (iii) 2FeSO4→ Fe2O3 + SO2+ SO3 (iv) NH4Cl → NH3 + HCl (v) 2Ca + O2→ 2CaO
(i) Decomposition. (ii) Combination. (iii) Decomposition. (iv) Decomposition. (v) Combination.
- ChemistryClass 10ICSE
Write one equation each for the decomposition reactions where energy is supplied in the form of (a) heat, (b) light, and (c) electricity.
Decomposition reaction when heat is supplied 2Pb(NO3)2→ 2PbO + 4NO2 + O2 Decomposition reaction when light is supplied 2AgCl → 2Ag + Cl2 Decomposition reaction where electricity is supplied 2H2O→ 2H2 + O2
- ChemistryClass 10ICSE
Name two anti-oxidants which are usually added to fat and oil containing foods to prevent rancidity.
Anti-oxidants are used as preservatives in fat containing foods to slow up the development of rancidity due to oxidation Butylated hydroxytoluene (BHT) and Butylated hydroxyanisole (BHA) can also be used as anti-oxidants with greater half-life than natural anti-oxidants.
- ChemistryClass 10ICSE
What type of chemical reaction is used to extract metals from their naturally compounds like oxides or chlorides?
Decomposition reaction is used to extract several metals from their naturally occurring compounds like oxide and chloride Example: 2NaCl → 2Na + Cl2
- ChemistryClass 10ICSE
Give one example of a decomposition reaction which is carried out: (a) With electricity By applying heat
When electricity is passed through acidified water it decomposes to Hydrogen and oxygen gas 2H2 O → 2H2 + O2 By applying heat, thermal decomposition takes place 2NaHCO3(s) → CO2(g) + H2O(g) + Na2CO3(s) Heating of baking soda is an example
- ChemistryClass 10ICSE
Explain why, food products containing fats and oils (like potato chips) are packaged in nitrogen.
The packet of chips or foods containing fats and oils are flushed with nitrogen. This is because nitrogen acts as a antioxidant and this packaging is to prevent the food products from being oxidized. If we pack with oxygen it reacts and become rancid and the smell and taste will change and will start to decay.
- ChemistryClass 10ICSE
What are anti-oxidants? Why are they added to fat and oil containing foods?
Anti-oxidants are the chemicals which are added to fat and oil containing foods to slow or delay the development of rancidity. Natural Anti-oxidants are ascorbic acid ad tocopherols whereas synthetic anti- oxidants include Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT). Anti-oxidants can be nutrients as well as enzymes that are especially proteins that can assist in chemical reaction and prevent development such as cancer,heart attack and many other chronic diseases
- ChemistryClass 10ICSE
State an important use of decomposition reactions.
Decomposition of silver chloride into silver and chlorineby light is used in photography. In the human body, this reaction helps in digestion of food in the stomach. Decomposition reaction is used in the manufacture of cement and gypsum. This reaction is used in the process of welding.
- ChemistryClass 10ICSE
What is the general name of the chemicals which are added to fat and oil containing foods to prevent the development of rancidity?
Anti-oxidants are the chemicals which are added to fat and oil containing foods to slow or delay the development of rancidity. Natural Anti-oxidants are ascorbic acid ad tocopherols whereas synthetic anti- oxidants include Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT)